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Clinical presentation of patients with Aromatic L-amino Acid Decarboxylase (AADC) Deficiency

Select a patient profile to review

Patient 1: 5-month-old female with developmental delay and dystonia

Not a real patient. Hypothetical profile based on actual patient findings.

History and presentation1

  • Began experiencing temperature instability and problems with breastfeeding immediately after birth
  • Excessive irritability noted at 2.5 months, including being startled by noises and sudden movements
  • Oculogyric crises that began at age 3 months, typically occurring in the late afternoon or evening; with increased frequency and severity over the following 2 to 5 months
  • Axial hypotonia
  • Right-sided head deviation
  • Unable to reach for objects, roll over, or lift head while in prone position
  • Ptosis, miosis, nasal congestion, drooling
  • Treated with clonazepam, which was not effective in mitigating oculogyric crises

Imaging1

  • Brain MRI: normal

Laboratory findings1

  • Metabolic screening: normal
  • Plasma AADC activity: undetectable

CSF neurotransmitter metabolite analysis

Metabolites

Results

3-OMD

1439 nmol/L

High

5-HIAA

9 nmol/L

Low

HVA

14 nmol/L

Low

Pterins

Normal

Normal

3-OMD=3-O-methyldopa; 5-HIAA=5-hydroxyindoleacetic acid; CSF=cerebrospinal fluid; HVA=homovanillic acid; MRI=magnetic resonance imaging.

Patient 2: 17-year-old male with dystonia of unclear etiology

Not a real patient. Hypothetical profile based on actual patient findings.

History and presentation2

  • Initially diagnosed with cerebral palsy at age 6 months after presenting with feeding difficulty, hypotonia, and episodes of tongue thrusting and oculogyric crises
  • Frequency and duration of episodes increased during adolescence, occurring every 2 days and lasting up to 8 hours
  • Patient did not achieve any developmental milestones, remained nonverbal
  • Temperature instability, hypotension
  • Severe insomnia
  • Previously treated with haloperidol, which led to increased frequency of oculogyric crises and dystonic symptoms

Laboratory findings1,2

  • Metabolic screening: normal
  • Plasma AADC activity: undetectable

CSF neurotransmitter metabolite analysis

Metabolites

Results

3-OMD

539 nmol/L

High

5-HIAA

24 nmol/L*

Low

HVA

50 nmol/L*

Low

Pterins

Normal

Normal

3-OMD=3-O-methyldopa; 5-HIAA=5-hydroxyindoleacetic acid; CSF=cerebrospinal fluid; HVA=homovanillic acid.

*Actual values for this patient case study were not available, so hypothetical values were added. Reference ranges vary by laboratory, and hypothetical values were based on reference ranges of 63–503 nmol/L for 5-HIAA and 176–955 nmol/L for HVA.1

References: 1. Swoboda KJ, Hyland K, Goldstein DS, et al. Clinical and therapeutic observations in aromatic L-amino acid decarboxylase deficiency. Neurology. 1999;53(6):1205-1211. 2. Anselm IA, Darras BT. Catecholamine toxicity in aromatic L-amino acid decarboxylase deficiency. Pediatr Neurol. 2006;35(2):142-144.